Propellant compositions



tions.

United States Patent lice 3,127,735 PROPELLANT COMPOSITIONS George L.Bauerle, Canoga Park, and Robert C. Ahlert and Jacob Silverman, WoodlandHills, Califi, assignors to North American Aviation, Inc.

No Drawing. Filed July 5, 1960, Ser. No. 40,576 8 Claims. (Cl. 60-354)This invention relates to novel propellant composi- More particularly,this invention relates to propellant compositions having reducedignition delay characteristics.

Initial fuel ignition in rocket motors and jet engines,

when hypergolic propellants are employed, is brought about upon contactof an oxidizer and a fuel. When non-hypergolic propellants are employed,smooth ignition is accomplished in many combustion devices by theinitial use 'of hypergolic or pyrophoric mixtures. One method ofinitiating combustion is by injecting the hypergol into the combustionchamber where it is to react with either of the main propellants. Ofnecessity, this hypergolic reaction must be very rapid so that reliableand safe ignition may be accomplished before an explosive mixture of themain propellants has filled the combustion chamber.

It is, therefore, an object of this invention to provide novel fuelcompositions. Another object of this invention is to provide fuelcompositions which have a lower ignition delay characteristic uponcontact with an oxidizer. It is also an object of this invention toprovide propellants which are spontaneously combustible. Another objectis to provide fuels and propellants which ignite smoothly in thecombustion chamber, minimizing danger of explosion. It is also an objectto provide fuels for rocket, jet, and ramjet engines having improvedignition characteristics. Still other objects of the invention will beapparent from the discussion which follows.

The above and other objects of this invention are accomplished byproviding a composition of matter comprising compounds having thegeneral formula R M, wherein R is selected from the group consisting ofhydrogen, halogen atoms, and hydrocarbon groups having from 1 to about12 carbon atoms and wherein at least one R is a hydrocarbon group; m isa metal selected from the class consisting of groups IA, II-A, IL-B,III-A, IV-B, IV-A, and V-A of the periodic table of elements; and x isthe valence of M, and wherein said composition contains at least twodiiierent metals in the form of said compounds, and wherein the amountof each of said compounds varies from about 0.1 weight percent to about99.9 weight percent, based on the total weight of said composition. Anexample of the above composition is triethylboron containing weightpercent triethylaluminum. Such a fuel composition, when contacted withliquid oxygen in a combustion chamber, ignites within about 1millisecond after contact and burns smoothly thereafter.

The hydrocarbon groups which make up a part of the meta1-containingcompounds of this invention can-be alkyl, aryl, arylkyl, and alkarylgroups and can be either straight chain, branch chain, or cyclic.

The halogen atoms included in the compounds employed in the compositionsof this invention are chlorine, bromine, fluorine, and iodine.

3,127,735 Patented Apr. 7, 1964 Non-limiting examples of organic-alkalimetal compounds that are used in the compositions 'of this inventioninclude methyllithium, ethyllithium, propyllithium, butyllithium,isobutyllithium, n-amyllithium, cyclohexyllithium, dodecyllithium,phenyllithium, alpha-napthyllithium, methylsodium, ethylsodium,propylsodium, butylsodium, cyclohexylsodium, octylsodium, dodecylsodium,phenylsodium, naphthylsodium, triphenylmethylsodium, methylpotassium,ethylpotassium, amylpotassium, dodecylpotassium, phenylpotassium,naphthylpotassium, ethyl rubidium, butylmbidium, phenylrubidium,dodecylrubidium, diphenylmethylrubidium, ethylcesium, butylcesium,octylcesium, dodecylcesium, phenylcesium, naphthylcesium, etc.

Non-limiting examples of group II-A metal-organic compounds includedimethylberyllium, dibutylberyllium, didodecylberyllium,dinaphthylberyllinm, methylberylliumhydride, phenylberylliumhydride,methylberylliumchloride, ethylberylliumbromide, etc.

Non-limiting examples of group II-B metal-organic compounds includedimethylzinc, diisobutylzinc, ethyl-n propylzinc, didodecylzinc,methylphenylzinc, ethylnaphthylzinc, methylzinchydride,ethylzincchloride, propylzincbromide, dimethylcadmium, diethylcadmium,octylbutylcadmium, didodecylcadmium, diphenylcadmium,naphthylmethylcadmium, ethylcadmiumhydride, phenylcadmiumhydride,methylcadmiumfluoride, naphthylcadmiumiodide, etc.

Non-limiting examples of group III-A metal-organic compounds includedimethylethylborine, triethylborine, tri-n-propylborine,tri-i-butylborine, tri-n-butylborine, trit-butylborine,tri-i-amylborine, trioctylborine, tridodecylborine,diphenylmethylborine, naphthyldiethylborine, trialpha-naphthylborine,phenylborinedichloride, dimethylborinebromide, dimethylborineiodide,methylborinedifluoride, dirnethylborinefiuoride, naphthylborinedioidide,dimethyldiborane, tetramethyldiborane, triethyldiborane,didodecyldiborane, trimethylaluminum, triethylaluminum,tri-n-propylaluminum, tributylaluminum, methyldiethylaluminum,ethyldibutylaluminum, trioctylaluminum, tridodecylaluminum,triphenylaluminum, trinaphthylaluminum, dimetbylaluminumhydride,ethylmethylaluminumhydride, dioctylaluminumhydride,octaylaluminumdihydride, naphthylaluminumdihydride, dimethylaluminiurmfluoride, methylalurninumdichloride, diethylaluminumiodide,cyclohexylaluminurndiiodide, diphenylaluminumbromide, trimethylgalliurn,methyldiethylgallium, diethylbutylgallium, trioctylgallium,triododecylgallium, trinaphthylgallium, dimethylgalliinnhydride,ethylgalliumdihydride, dodecylgalliumdihydride, dimethylgalliumchloride,diethylgalliumchloride, dibutylgalliumbromide, dodecylgalliumdiiodide,trimethylindium, tributylindium, diethyldodecylindium,dimethylindiumhydride, dodecylindiumdihydride, dimethylindiumchloride,octylindiurndifluoride, naphthylindiumdibromide, trimethylthallium,triethylthallium, methyldidodecylthallium, naphthyldibutylthalliurn,dimethylthalliumhydride, naphthlythalliumdihydride,dimethylthalliumchloride, octylthalliumdibromide, etc.

Non-limiting examples of group IV-A metal-organic compounds includetetramethylgermaniurn, dimethyldiethylgermanium,diphenyldiethylgermanium, tetradodecylgermanium,naphthyltriethylgermanium, ethylgermaniumtrihydride,dipropylgermaniumdihydride, tridodecylgermaniumdihydride,dioctylgermaniumdifluoride, triododecylgumaniumiodide, diphenylgenaniumdifluoride, etc.

A non-limiting example of a group IV-B metal-organic compound isdiphenyl-bis cycylphenyldieniyltitanium.

Non-limiting examples or group V-A metal-organic compounds includetrimethylarsine, methyldiethylarsine, tributylarsine,cyclohexyldiethy-lars-ine, trioctylarsine, tridodecylarsine,naphthyldiethylarsine, tetnaethyldiarsine, tetraethyldiarsyl,dimethylarsenichydride, ethylarsenicdihydnide, diphenylarsenichyd-ride,dimethylarsenicchloride, diethylarse-nicfluoride,phenylarsenicdibromide, tnimethylstibine, methyldiethylstibine,tributylstlbine, cyclohexylstibine, tr-ioctylstibine,tridodecylsti-bine, naphthyldiethylstibine, dimethylantimonyhydride,ethylantimonydihydride, diphenylantimonyhydride,dimethylantimonychloride, diethylantimonyfluoride,phenylantimonydibromide, trimethylbismuth, triethy-lbismuth,tridodecylbi-smu-th, tuiphenylbisrnuth, trinaphthylbismuth,dimethyl-bismuthhydi'ide, ethylbismuthdihydride,didodecylbismuthhydmide, dimethylbismuthhydride, ethylbismuthdihydride,diphenylbismuthhydnide, dirnethylbismuthchloride,diethy-lb-ismuthfluoride, phenylbismuthdibromide, etc.

It is found that when the compositions contain at least two differentmetals in the form of compounds having the general formula R M theignition delay, defined as the time elapsi-ng from the moment f contactof the iuel with an oxidizer to the moment of ignition, is lower thanthe calculated ignition delay, based on the concentnation of the variouscomponents of the mixture and the known ignition delay period .for thepure individual compounds. A great reduction in the ignition delaycharacteristic is [found upon mixing boron-organic compounds with othermetal-organic compounds of the class disclosed hereinabove. Fuelcompositions containing boronorganic compounds, theretfiore, constitutea preferred embodiment of this invention. An additional advantageresulting from the use of iuels containing boron is that the boron oxideresidue is less adherent to the surfaces of combustion and thrustchambers and can be readily removed because of its water solubility.

The ignition delay determinations were measured by noting the timebetween the contacting of the propellants, namely, the fuel andoxidizer, and the time of ignition in an unconfined combustion zone. Oneor the other of the propellants was given a substantial lead (in mostoases, the first propellant was the oxidizer), and the second propellantwas then admitted. The iuel passed a photocell very near the impingementpoint of the two propellants. The start of ignition was noted as anevolution of visible light, also registered on a photocell. Thesesignals were recorded on an oscillograph which made measurements .to :1millisecond. Ignition delays have also been determined in small motorsin which the propellants are contacted. The ignition point is then alsoevidenced by a rise in chamber pressure. The measure ments were made atan ambient pressure equivalent to substantially 715 mm. of mercury.

As stated hereinaboye, the amount of each metal-organic compound in thecomposition can vary from about 0.1 to about 99.9 Weight percent sincesuch compositions exhibit ignition delay periods lower than thatexpected from :a knowledge of the ignition delay periods of theindividual components in the pure state and the weight percent of thecomponents in the composition. it is found, for example, that theignition delay period upon contacting liquid oxygen with triethylboronis substantially 111 milliseconds, and the ignition delay uponcontacting liquid oxygen with triethylaluminum is 9 milliseconds.

The following table illustrates the ignition delay characteristics or acomposition of boron-organic compounds and aluminum-organic compounds.The ignition delay of the system is determined as described above.Liquid oxygen is first admitted to the combustion zone, followed by theadmission of the fuel which contacts the liquid oxygen.

TABLE I Triothyl- Triethyl- Ignition Ignition boron, aluminum, Delay,Delay, Comp. No. Wt. Wt. Milli- Milli- Percent Percent seconds, seconds,

Calculated of Mixture From the above table it is seen that .a greatreduction in the ignition delay characteristics of a iuel is obtainedwhen two difierent metals in the form of metal-organic compounds arepresent, as compared with the sum of the ignition delay characteristicsof the individual components multiplied by the weight percent of thatcompo nent in the composition. The maximum reduction in ignition delayof the triethylboron-niethylaluminum system is observed with CompositionNo. 5 in Table I, namely, weight percent triethyl-bzoron (TEB) and 5weight percent triethylaluminum (TEA). The calculated ignition delayperiod is 106 milliseconds, whereas the observed ignition delay is onlyone millisecond. This is a reduction of 99.9% in the ignition delay.

The values given in Table I hold true for values of the ratios ofoxidizer-to-fuel given in terms of multiples oi the stoichiometricweight ratio value of irom about 0.1 to about 30. The values in Table Irepresent an average obtained from about 50 determinations for theindividual fuel formulations. The fuels exhibit a reduction in ignitiondelay when employed with nitrogen tetroxide and other oxidizersdiscussed below.

Other fuel compositions which exhibit an ignition delay period which islower than that calculated from a knowledge of the weight percentcomposition and the ignition delay period for the pure components, whenemployed with liquid oxygen, nitrogen tetroxide, and the other oxidizersdiscussed in this writing, are given in Table 11 below.

TABLE II Composition No. Component Weight Percent {ButylhthiuimEthylpotasslum {Alpha-naphthyllithium Ethyl rubidium-.-

{Ethylsodlum Dibutylberyllium.

7 {Butylrubidium Methylberylliumchloride DodecylcesiumDinaphthylberyllium Dimethylberyllium.

10 {Propyllithium Dirnethylzine 11 {Ethylsodium ensure {PhenylrubldiumMethyleadmlumfiuorid {Phenylpotassium Propylzincbr omide{Isobutyllithium Trioctylborine- {Amylpotassium'Irl-alpha-naphthylborine.

19 {Ethylrubidium Tetramethylldib crane 5 TABLE IIContinued CompositionNo. Component Weight Percent Butylsodium 50 2O Ethylpntassinm 49 5Methylborinedifiuoride 0. 5 Naphthylp otassium 5 21 Triethylborine 45Tri-alpha-naphthylborine.-- 50 Ethylpot assium 90 22 {Butyllithium 5Dipheny1methy1borine 5 D odecyllithium 20 Oetylsodinm 30 Triethylborine50 24 {Butylsodium 99. 9 Trimethylindnun. 0, 1 25 {Ethylpotassium 99Naphthylaluminumdrhydri e 1 26 Phenylpotfissium- 99Dimethylgalliurnfluonde 1 27 {D odecylpotas sium- 50 Trioctylalummum. 5028 {Phenyllithiuni 5 Triethylalurninum. 95 29 {Triphenylmethylsodium 1Tributylaluminum 99 30 {Phenylcesiun 0, 1 Trioctylalunnnum 99. 9 31Ethylp otassium 99, 9 Diphenylgermaniumdrfiuoride. 0, 1 32 {Octylsodiurnr 99 Ethylgermaniumtrrhydnde. 1 33 {Methyllithium 1 Tetramethylgermanlum99 34 {Phenylrubidium 99. 9 Tetradodeoylgermamum 0. 1 3 5 {Dodecyllithium 99. 9 Trimethylarsme. 0. 1 36 {Butylsodiuln 99Ethylarsenicdihydride 1 37 {Phenylrubidiumu 0. 1 Tributylstibine. 99. 938 {Methylpotassiurm 0. 1 Trimethylstibine 99. 9 39 {Oyc1ohexy1sodium 95Diphenylbismuthhydride. 5 Ethylpotassium 50 40Diphenyl-biseyclophenyldieniyltitanium 50 41 {Dibuty1beryl1ium. 99. 9Phenylcadmiumhydride. 0. 1 42 Dido decylberyllium... 99 Dimethylzinc. 143 Phenylberyllium 0. 1 Ethyl-n-propylzine. 99, 9 44 {Ethylzincchloride99 Methylberylliumchlonde. 1 45 {D imethylberyllium 99 Triethylborine 146 {Dibutylberylllum 1 ""T""".' Tri-n-butylborine 99 47 {Dimethylberyllium. 1 Triethylalurninum 99 4 {Dido decylberyllium... 99 8Tridodecylaluminum- 1 49 {Didodecylberyllium 99 -TTetradodecylgermaniurm. 1 50 {Methylberylliumchlorfle 1Dirnethyldiethylgermamum. 99 51 {Dibutylberyllium 99 Trimethylarsine 1 2{Dinaphthylberyllium 1 5 Triethylbismuth 99 53 {Dimethylzine 99, 9grietlllylborinel. 0. g

t y -n-propy zinc 9 54 {Dimethylborinebromidan 1 {Dido decylzine 5Tri-n-butylborine. 95 {Diisobutylz'menn 95 Tridodeoylborinen 5 5{Dimethylzino 99 7 Naphthaldiethylborine 1 58 D iisobutylzinc 99. 9Phenylborinedichlonde--. 0.1 9 {Diethy1oadmium 50 5 Triethylborine. 5060 {Triethylbrine. 99. 9 Trimethylalurninuim. 0.1 Trim-propylborine- 1061 Triethylborine 89 Dimethylalurninumhydride. 1 I Dimethylborinebromide1 62 Tri-i-butylborine 4 Triethy1a1u1ninum 90 Diethylaluminumio dide'Irido decylborine .5 63 Tri-n-butylborine. 90 Tributy1aluminum 4Ootylaluminumdihydride. 1 Dimethylethylboriue.-. I. 5Diphenylmethylborine. OZ 5 Methyldiethylaluminum. 90Methyldiethylgallium 9 4 Triethylborine. 0. 1 65 Trioctylaluminum 99Trimethylindium. 0.9

Weight Percent Composition No. C omponent 66 {TriethylborineDimethyldiethylgermanium- 67 {D1pheny1methy1borine.

------------ Tetramethy1germanium {Triethylborine 68Methyldiethylarsine.

Trioctylstibine 'Iridodecylborine 69. TriethylbismuthPhenylantimonydibromide Triethylaluminum EthyhnethylaluminumhydriDiethylbutylgallium Dimethyldiethylgermanium.Dipropylgermaniumdihydride. Tri-n-propylaluminum Methyldiethylgallium-Dirnethylindiumhydride Methyldiethylarsine. EthylantimonydihydriTridodecy1a1uminum Trimethylgalllun1 TriethylthalliumDiphenyldiethylgermanium- Trimethylarsine 'IributylstibineNaphthylcesiu.m

Dimethylbismuthohlori e The oxidizers with which the fuels of thisinvention exhibit reduced ignition delay periods include liquid oxygen,nitrogen tetroxide, hydrogen peroxide, chlorine trifluoride, brominepentafluoride, White fuming nitric acid, red fuming nitric acid, liquidfluorine, liquid fluorine and liquid oxygen mixtures of from about 5 toabout mole percent fluorine in oxygen, perchlorofluoride having thegeneral formula FClO and nitrogen trifluoride, mixed 'oxides ofnitrogen, as well as other oxidizers known to those skilled in the art.

The amount of oxidizer employed with the fuel is given in terms of thestoichiometric ratio of oxidizer-to-fuel. The stoichiometric value ofthe ratio is defined as that value of the weight ratio when the oxidizerand fuel are used in stoichiometrical portions for complete oxidizationof the fuel. The oxidizer-to-fuel weight ratio can vary from about 0.1of the stoichiometric ratio value to about 30 times the stoichiometricratio value for ignition purposes. When, however, the metal-organiccompounds are employed as components of improved hydrocarbon fuelmixtures, the oxidizer-to-fuel ratio varies from about 0.5 to about twotimes the stoichiometric ratio value. For better engine performance withrespect to thrust and range, however, oxidizer-to-fuel weight ratiosequivalent to from about 0.6 to about 1 of the stoichiometric value arepreferred.

Liquid oxygen is found to perform well when employed as the oxidizerwith the fuels of this invention. Therefore, the use of liquid oxygenconstitutes a preferred embodiment of this invention. 7

The performance of the compositions of this invention as rocket fuelswas investigated by operating stationary rocket motors using the fuelstogether with a suitable oxidizer. The rocket engine employed in thetests had a throat area of 0.132 square inch. The ratio of the crosssectional area of the nozzle exit-to-throat cross sectional area was1:1. The ratio of the cross sectional area of the combustionchamber-to-the cross sectional area of the throat was 2.0: l. The motorwas operated at a combustion chamber pressure of 500 p.s.i.a. and anexit nozzle pressure of substantially 13.6 p.s.i.a. The fuel compositionand oxidizer were fed through separate conduits from individual storagecontainers to the combustion chamber where the stream of fuelcomposition and the stream of oxidizer contacted each other uponemerging from orifices in an injector plate. The fuel and oxidizerignited upon contact, producing gaseous products as a result of thespontaneous combustion of the components of the two streams. The gaseousproducts were ejected from the combustion chamber through the throatarea and then out into the atmosphere through the exit nozzle. Theejection of the reaction product gases from the combustion chamberproduces a thrust which is measured by means of a load cell mountedforward of the motor. The fuel composition and the oxidizer were meteredinto the motor so that the amount reacting within any particular periodof time was known.

In instances where the fuel compositions do not make completely fluidsolutions, a solvent is used which also serves as a fuel. Non-limitingexamples of solvents used include benzene, chloroform, and hydrocarbonfuels of the type discussed below.

Non-limiting illustrative examples of the operation of rocket motorsdescribed above employing the fuel compositions of this invention aregiven below.

Example I The rocket motor described above is operated on fuelcomposition No. 2 of Table I, using liquid oxygen as the oxidizer. Theoxidizer-to-fuel weight ratio is equivalent to the stoichiometric value.The ignition of the fuel in the engine is smooth and the engine operatessatisfactorily.

Example II The above rocket motor is operated with fuel No. 9 of TableI, together with a liquid oxygen-fluorine mixture in the Weight ratio of95:5, oxygen-to-fiuorine. The ratio of oxidizer-to-fuel is substantially0.6 of the stoichiometric ratio value. A smooth ignition andsatisfactory operation is observed.

Example III The above rocket motor is operated on fuel No. 3 of Table I,with liquid oxygen as the oxidizer. The oxidizerto-fuel weight ratio is0.1 of the stoichiometric ratio value. Improved ignition andsatisfactory operation is observed.

Example IV The above rocket motor is operated on fuel No. 8 of Table I,together with liquid oxygen. The oxidizer-tofuel weight ratio is 30times the stoichiometric ratio value. Improved ignition and satisfactoryoperation is observed.

Example V The procedure of Example IV is repeated employing compositionNo. 4 of Table I as the fuel and nitrogen tetroxide as the oxidizer. Theoxidizer-to-fuel weight ratio is substantially 0.8 of the stoichiometricratio value. Smooth ignition and efiicient operation is observed.

Example VI The procedure of Example IV is repeated employing fuel No. 5of Table I, together with liquid oxygen as the oxidizer. Theoxidizer-to-fuel weight ratio is ten times the stoichiometric value.Smooth ignition and satisfactory operation are observed.

Example VII The above rocket engine is operated on fuel No. 16 of TableII, together with liquid oxygen in proportions equivalent to thestoichiometric values of the oxidizer and fuel. Smooth ignition andsatisfactory operation are observed.

Example VIII The rocket motor described above is operated on fuel No. 55of Table II, with a liquid oxygen-fluorine weight percent mixture of76-to-24, oxygen-to-fluorine, as the oxidizer. The oxidizer-to-fuelweight ratio is 0.6 of the stoichiometric ratio value. Smooth ignitionand satisfactory operation are observed.

8 Example IX The above rocket motor is operated on fuel No. 71 of TableII, together with hydrogen peroxide as the oxidizer. Theoxidizer-to-fuel weight ratio is equivalent to 0.7 of the stoichiometricratio value. Improved ignition and satisfactory operation are observed.

Example X Improved ignition and satisfactory operation are observed whenthe above rocket motor is operated on fuel No. 73 of Table II, togetherwith nitrogen tetroxide as the oxidizer. The oxidizer-to-fuel ratio is30 times the stoichiometric ratio value.

Example XI The procedure of Example X is repeated with the modificationthat fuel No. 69 of Table II is employed, together with white fumingnitric acid as the oxidizer. The oxidizer and fuel are employed inproportions equivalent to the stoichiometric values for completecombustion of the fuel. Improved ignition and satisfactory operation areobserved.

Example XII The procedure of Example X is repeated employing fuel No. 10of Table II, together with liquid oxygen as the oxidizer. Theoxidizer-to-fuel weight ratio is equivalent to the stoichiometric valueSmooth ignition and satisfactory operation are observed.

In like manner, improved ignition and satisfactory operation of therocket motor are observed when the other fuels of Tables I and II areemployed with the oxidizers specified hereinabove.

When a flight rocket is operated on the composition No. 5 of Table I,together with liquid oxygen as the fuel in proportions such that theoxidizer-to-fuel ratio is equivalent to the stoichiometric ratio value,satisfactory flight performance is observed.

In like manner, satisfactory performance is observed when flight rocketsare operated on fuel compositions of Tables I and II, together withliquid oxygen and the other oxidizers specified hereinabove.

The compositions of this invention are employed not only as primaryfuels but also as additives to other hydrocarbon fuels having boilingpoints within the range of from about 87 F. to about 600 F. For example,the combustion characteristics of solene is improved by the addition offrom about 1 to about 99 Weight percent of the compositions describedhereinabove, including those given in Table I. Solene is a hydrocarbonfuel having an initial boiling point (IBP) of about 90 F. and a finalboiling point (FBP) of about 406 F. It is composed of 20.8 weightpercent thermal distilate, 21.5 weight percent catalytic distillate,26.4 Weight percent virgin naphtha, and 1.3 weight percent butane. Aspecific example of a hydrocarbon fuel is solene containing 1 weightpercent of composition No. 3 of Table I. Another fuel that is improvedby the additions of the compositions described hereinabove is indolene.Indolene has an initial boiling point of substantially 94 F. and a finalboiling point of substantially 390 F. In'dolene is a brand ofstraight-run catalytically cracked and polymeric blending stockscontaining 10 weight percent of polymeric components, 40 weight percentcatalytically cracked heavy naphtha, 35 weight percent virgin lightnaphtha, 5 weight percent butane, and 10 weight percent pentane. Aspecific example employing indolene fuel is a composition containing 99weight percent of composition No. 5 of Table I and 1 weight percentindolene.

Non-limiting illustrative examples of fuel compositions of thisinvention employing a hydrocarbon fuel as one of the components 'aTegiven in Table III below.

9 TABLE III Components Weight Percent Composition No. 3 of Table I 1.TP-4

3 {Composition N o. 8 of Table I Fuel A Composition No. 2

Benreno {Composition No. 9 of Table L--- Kerosene Composition No. 48 ofTable II CHCl Benzene {Composition N 23 of Table 11.. Fuel B FuelA isahydrocarbon fuelhaving an IBP of 87 F, a FBP of 600 F., with anaromatic content of 25 vol. percent max, and an olefin content of 10vol. percent max.

b Fuel B is a hydrocarbon fuel having an IBP of 400 F., a FBP of 600 F.,a flash point of 190 F., with an aromatic content 015 vol. percent max.,and an olefin content of 1 vol. percent max.

The JP-4 fuel is a hydrocarbon fuel having an IBP of about 144 F., a.FBP of about 487 F an aromatic content of about 11.3 vol. percent and abromine number of about 1.59.

The fuel designated as RP-l has an IBP of about 350 F. and an FBI ofabout 525 F., a flash point of about 110 F., an aromatic content of 5vol. percent max., and an olefin content of 1 vol. percent max.

Non-limiting illustrative examples of the use of fuels of the type shownin Table III are given in the following examples.

Example XIII A jet engine is operated on IP-4 fuel containing 1 weightpercent of composition No. 3 of Table I. Good ignition and satisfactoryoperation of the engine are observed.

Example XIV A ramjet engine is operated on composition No. 2 of TableIII. Satisfactory operation is observed.

Example XV A space rocket vehicle is powered by composition No. 2 ofTable III, together with 'liquid oxygen as the oxidizer. Satisfactoryoperation is observed.

In like manner, satisfactory operation is observed when jet engines,namjets, or space flight vehicles employ hydrocarbon fuels having an IBPin the range of from about 87 F. to about 400 F. and la FBP of fromabout 450 F. to about 600 F., together with the compositions of Tables Iand II for propulsion purposes.

Example XVI A rocket motor having a regeneratively-cooled thrust chamberand rated at 100,000 pounds thrust was operated on a combination of RP-lfuel and liquid oxygen in stoichiometric proportions. The liquid oxygenwas admitted first to the combustion chamber. A hypergol consisting of amixture of 96 weight percent triethylborine and 4 weight percenttriethylaluminum was next admitted to the combustion chamber precedingthe fuel, where it contacted the liquid oxygen and ignition occurred.While the hypergol and the liquid oxygen burned, RP-l fuel was admittedfrom a pressurized tank to the combustion chamber where it ignitedsmoothly and satisfactory operation of the motor thereafter wasobserved.

Equally good results are obtained when the procedure of Example XVI isrepeated employing a hypergol consisting of a mixture of 85 weightpercent triethylborine and 15 weight percent triethylaluminum. Likewise,smooth ignition is obtained when combustion in a rocket motor isinitiated by the use of one of the fuel compositions of Tables I and IIwith liquid oxygen, as well as with other compositions of the typesdescribed hereinabove with a suitable oxidizer and a hydrocarbon fuel 10having an IBP of from about 87 F. to about 400 F: and an FBP from about450 F. to about 600 F. is fed to the combustion chamber while thehypergol and the oxidizer are undergoing combustion. Thus, the method ofExample XVI is used to initiate ignition of any of the hydrocarbon fuelsdiscussed above.

By the use of a hypergol consisting of a fuel composition containingcompounds having the general formula R M, as described hereinabove,wherein the composition contains at least two different metals in theform of these compounds, smooth ignition is accomplished. This methodprovides a reliability factor in the start up of engines which minimizesthe danger of forming an explosive mixture in the combustion chamberprior to ignition.

From the discussion and examples given hereinabove, it is seen thatnovel fuel compositions have been provided. A word of caution withrespect to the preparation and use of these compositions may be inorder. Many of the organo-metallic compounds, as well as the fuelformulations, are highly explosive, and explosions may occur even whenit is believed that all safety precautions have been observed. It is,therefore, advisable to treat all fuel compositions as highly explosiveand dangerous materials for handling purposes.

While the compositions and method of this invention have been describedin some detail, with the use of specific illustrative examples, it is tobe understood that the examples were used by way of illustration onlyand not by way of limitation. It is not intended that the spirit orscope of this invention be limited except as indicated in the appendedclaims.

We claim:

1. A method of effecting combustion in a reaction chamber with a minimumof ignition delay between a fuel composition and an oxidizer forcombusting said fuel composition, the method comprising contacting insaid reaction chamber said oxidizer with said fuel composition, saidfuel composition comprising a boron compound having the formula R 13 andfrom one to about 99 weight percent, based on the total weight of thecomposition, and an aluminum compound having the formula R Al, andwherein each R is an alkyl hydrocarbon group having from one to about 12carbon atoms.

2. A method of effecting combustion in a reaction chamber with a minimumof ignition delay between a fuel composition and an oxidizer forcombusting said fuel composition, the method comprising contacting insaid reaction chamber said oxidizer with said fuel composition, saidfuel composition consisting essentially of a boron compound having theformula R B and from one to about 99 weight percent, based on the totalweight of the composition, and an aluminum compound having the formula RAl, and wherein each R is an alkyl hydrocarbon group having from one toabout 12 carbon atoms.

3. A method of effecting combustion in a reaction chamber with a minimumof ignition delay between a fuel composition and an oxidizer forcombusting said fuel composition, the method comprising contacting insaid reaction chamber said oxidizer with said fuel composition, saidfuel composition consisting essentially of from one to 99 weight percenttriethylaluminum and from 99 to one weight percent triethylboron basedon the combined weight of said triethylaluminum and said triethylboron.

4. A method of initiating combustion in a reaction chamber with aminimum of ignition delay between a hydrocarbon fuel boiling within therange of 90 F. to about 600 F. and an oxidizer for combusting said fuel,the method comprising first contacting in said reaction chamber saidoxidizer with a composition comprising a boron compound having theformula R B and from one to about 99 weight percent, based on the totalweight of the composition, and an aluminum compound having the formula RAl, and wherein each R is an alkyl hydrocarbon group having from one toabout 12 carbon atoms, whereby said oxidizer and said compositionprovide 11 hypergolic ignition in said chamber, and thereaftercontacting said oxidizer with said hydrocarbon fuel.

5. A method of initiating combustion in a reaction chamber with aminimum of ignition delay between a hydrocarbon fuel boiling within therange of 90 F. to about 600 F. and an oxidizer for combusting said fuel,the method comprising first contacting in said reaction chamber saidoxidizer with a composition consisting essentially of a boron compoundhaving the formula R B and from one to about 99 weight percent, based onthe total weight of the composition, and an aluminum compound having theformula R Al, and wherein each R is an alkyl hydrocarbon group havingfrom one to about 12 carbon atoms, whereby said oxidizer and saidcombustion provide hypergolic ignition in said chamber, and thereaftercontacting said oxidizer with said hydrocarbon fuel.

6. The method of producing thrust comprising supplying to a combustionchamber a hydrocarbon fuel boiling in the range of from about 90 F. toabout 600 F. and an oxidizer for combusting said fuel, said hydrocarbonfuel containing from about 1 to about 99 weight percent of a compositioncomprising a boron compound having the formula R B and from one to about99 Weight percent, based on the total weight of the composition, and analuminum compound having the formula R Al, and wherein each R is analkyl hydrocarbon group having one to about 12 carbon atoms, andcombusting said fuel in said chamber.

7. The method of producing thrust comprising supplying to a combustionchamber a hydrocarbon fuel boiling in the range of from about 90 F. toabout 600 F. and an oxidizer for combusting said fuel, said hydrocarbonfuel containing from about 1 to about 99 Weight percent of a compositionconsisting essentially of from one to 99 weight percent triethylaluminumand from 99 to one weight percent triethylboron based on the combinedweight of said triethylaluminum and said triethylboron, and combustingsaid fuel in said chamber.

8. The method of claim 7 wherein said boron compound is triethylboronand said aluminum compound is triethylaluminum.

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1. A METHOD OF EFFECTING COMBUSTION IN A REACTION CHAMBER WITH AMINIMUMOF IGNITION DELAY BETWEEN A FUEL COMPOSITION AND AN OXIDIZER FORCOMBUSTING SAID FUEL COMPOSITION, THE METHOD COMPRISING CONTACTING INSAID REACTION CHAMBER SAID OXIDIZER WITH SAID FUEL COMPOSITION, SAIDFUEL COMPOSITION COMPRISING A BORON COMPOUND HAVING THE FORMULA R2B ANDFROM ONE TO ABOUT 99 WEIGHT PERCENT, BASED ON THE TOTAL WEIGHT OF THECOMPOSITION, AND AN ALUMINUM COMPOUND HAVING THE FORMULA R3AL, ANDWHEREIN EACH R IS AN ALKYL HYDROCARBON GROUP HAVING FROM ONE TO ABOUT 12CARBON ATOMS.